1. Field of the Invention
The invention relates to an ignition anode for, in particular, reignitable rocket combustion chambers.
2. Discussion of Background Information
A prior art ignition system made by Stork® Product Engineering B.V. is known by the name EGOX/GH2 VINCI EM Igniter. This is an igniter for reignitable rocket combustion chambers, whereby a gaseous hydrogen-oxygen mixture is ignited by means of electric ignition. An igniter 100 of this type is shown diagrammatically (in a longitudinal sectional view) in FIG. 6 of the instant application.
As can be seen in FIG. 6, the igniter 100 has an igniter housing 101 and a spark plug device 102. An igniter injection head 103 is located in the igniter housing 101, which igniter injection head, together with the igniter housing 101, forms an ignition mixing chamber 104. The ignition mixing chamber 104 opens into an ignition flame tube 105, which projects into the combustion chamber of the rocket to be ignited. The spark plug device 102 has a spark plug 106, which is arranged in a spark plug clamping ring 107. The spark plug 106 has a connection end 108 for connection to an ignition voltage source (not shown). An ignition anode 109 is located opposite the connection end 108, which ignition anode, together with the igniter injection head 103, forms an annular clearance 110, and the front side of which faces the ignition mixing chamber 104. A pipe connection 111 for a hydrogen supply and a pipe connection 112 for an oxygen supply are mounted on the igniter housing 101. Furthermore, measuring devices 113 are provided, e.g., in order to measure an ignition mixing chamber wall temperature.
The ignition anode 109 according to the prior art is shown enlarged in FIG. 6a in a partial longitudinal section. The ignition anode 109 has an essentially cylindrical structure 120 with a first free end 121. Opposite the first free end 121 the cylindrical structure 120 merges into a constricted section 122, which first narrows and expands towards an anode head section 123, the anode head section 123 having an enlarged diameter compared to the cylindrical structure 120. The anode head section 123 has a free end 124, which is formed by a flat frontal area 125 and an obtuse-angled chamfer 126. The free end 124 thus has a single annular edge. The flat frontal area 125 and the flat-angled chamfer 126 form an ignition frontal area, which in the assembled state faces into the igniter mixing chamber 104. An outside 127 of the anode head section 123, together with a corresponding bore in the igniter injection head 103, forms the annular clearance 110. From the free end 121 the ignition anode 109 has a blind-hole recess 128 in the cylindrical structure 120, by means of which blind-hole recess 128, the ignition anode 109 is connected to the spark plug 106 with suitable mounting means in an interacting manner.
An igniter of this type for reignitable rocket combustion chambers has proven to be valuable. However, a progressive erosion on the ignition frontal area is observed with a large number of reignition processes of the rocket combustion chamber. Likewise, an increased wear is established as a result of burn-off. Furthermore, when the rocket combustion chamber is switched off, an oxide layer forms on the ignition frontal area, which when the combustion chamber is reignited impairs the build-up of the plasma spark. This results in a possible increased operational risk.